Maastrichtian ammonites and biostratigraphy of the Sakhalin and the Shikotan Islands, Far Eastern Russia

Vol. 44, No. 3-4

ELENA A. YAZIKOVA

acta gaologlea polonica Warszawa 1994

Maastrichtian ammonites and biostratigraphy of the Sakhalin and the Shikotan Islands,

Far Eastern Russia

ABSTRACT: Stratigraphy, ammonite paleontoJogy, and regional characteristics are presented from the Maastrichtian deposits of the Sakhalin and the Shikotan IsJands, Far Eastern Russia.

Two different ammonite biostratigraphic zonal schemes based on the representatives of the family Desmooeratacea.e and the Tetragonitaceae, respectively, are established and their correlation with the Ja~ese ammonite zonation is suggested. All ammonites are monographed, and of the recogruzed 17 species, part is reported for the rust time from the Maastrichtian of the studied area,

the Kamchatka Peninsula including.

INTRODUCTION

The aim of the present paper is to describe the ammonite fauna and biostratigraphy of the Maastrichtian deposits of the Sakhalin and the Shikotan Islands, Far Eastern Russia. Besides inoceramids, the ammonites represent the second group allowing the refmed biostratigraphic subdivision of the topmost Cretaceous (Upper Campanian-Maastrichtian) strata of the area. Moreover, they provide an opportunity to the direct correlation on the global scale. The revised ammonite material contains also a relatively large collection yielded from the famous exposures of the Kamchatka Peninsula.

The field studies were carried out by the Author in the years 1986-89, mainly in the area of t,he Sakhalin Island. Over 20 sections were studied, with 150 ammonite specimens collected, and stratigraphically labelled in the column.

Four sections were selected for detailed works on the Shikhotan Island. For paleontological purposes the vast ammonite collections of the late Dr. V.N.

VERESHAGIN and Dr. J.O. MIROLUBOV, both from VSEGEI, St.-Peterburg, were also studied.

The subject of this paper forms a part of the Ph.D. thesis presented in 1993 at the PaleonWlogical Department of the Moscow University, and prepared under the supervision of Prof. Dr. I.A. MJlCHAILOVA.

278 ELENA A. YAZlKOVA

PREVIOUS RESEARCH

The first report on the Cretaceous deposits of the Sakhalin Island was published by SCHMIDT (1868), who gave the geological description and the faunal list of fossils collected during the expedition to the Cretaceous of Zhonker Cape; during the same expedition LoPATlN stated the presence of the Upper Cretaceous deposits at the eastern coasts of the Island. The paleo- ntological description of the fauna was completed some years later (SCHMIDT 1873), whereas MICHAEL (1899) gave a description of the radially ribbed inoceramids from that area.

At the turn of the century, there appeared a series of regional studies (fIKHONOVICH & POLEVOY 1915) as well as many paleontological descriptions of the inoceramid and ammonite faunas (JIMBO 1894, YABE 1909, SOKOLOV 1914). SOKOLOV (1914) regarded the radially ribbed inoceramids as being of Late Campanian age and the beds with l1Zoceramus ba/chi MEEK & HA YDEN as of Maastrichtian age. This opinion was accepted later in the whole northern Paciftc Region (Japan, Vancouver Island, and Alaska).

In 1917 the geological study of the area was undertaken by KRlSH- TAFOVITCH, who proposed the first local stratigraphic scheme for the Cretaceous ofSakhalin. The four stages distinguished by him (KRISHTAFOVlTOI 1920,1932), i.e. the Inuss, the Gylayk, the Orochern, and the Zagayan, correspond approximately to the Albian, Cenomanian-Turonian, lower Maastrichtian, and the· topmost Maastrichtian, respectively. His later pUblications (KRJSHTAFO- VITCH 1935, 1937) were devoted to the Cretaceous flora from the northern part of Sakhalin.

In 20 's and 30 's, the southern part of the Island was intensively studied by Japanese workers. YABE (1927), and later MATSUMOTO (1942-43), completed the scheme of the zonal subdivision of the Upper Cretaceous succession, including the very detailed ammonite and inoceramid zonation for the reference section on the river Nayba (see also MATSUMOTO 1959).

Since 1957 the comprehensive studies over the whole Sakhalin were undertaken by VERESHAOlN and his co-workers. Through many years of research they recognized the general succession, established the biostratig- raphic scheme (see e.g. VBRESHAOrN 1963, VERESHAOIN & al. 1961, 1978), as well as provided the description of the stratigraphically important fauna, including ammonites, inoceramids, and foraminifers (see e.g. PERGAMENT 1966, 1971, 1974; ZONOVA 1992 and papers cited herein; ZoNOVA & al. 1993;

YAZIKOVA 1992). They published also a very detailed description of the Nayba reference section (see POYARKOVA 1987) with the extended paleo- ntological characteristics of the faunal remains.

MAASTRlCIfiIAN AMMONITES

SAKHALIN ISLAND

!)() km

-

DOLPHIN SOUTH SAKHAlIN

AJlCTIC SE"-

Skm

SHIKOTAN ISLAND ItJI

Fig. 1

279

Location map of the reference sections in the Sakhalin Island and the Shiltotan IsJand, Far Eastern Russia

280 ELfiNA A. YA7JKOVA

GEOLOGIC SB1TING

The Upper Cretaceous deposits of the Sakhalin Island occur in three areas: (1) West Sakhalin Region, (2) East Sakhalin Region, stretching almost N-S along the western and eastern sides of the Island, respectively, and (3) Schmidt Peninsula, in the northernmost part of the Island (see Text-fig. 1).

Within the area of the West Sakhalin Region, the Upper Cretaceous deposits display quite a distinct, longitudinal facies change. Open marine, non-carbonate clasties in the south are gradually replaced northward by near-shore clasties passing in the northernmost part into continental, co- al-bearing strata.

The critical area for the purposes of this study is thus the southern part of the West Skhalin Region, providing marine, continuous and fossiliferous Maastrichtian (as well as the whole Upper Cretaceous) sections. They are exposed the best along the Nayba River and its tributaries, with the succession observed here representing the reference section for the whole Upper Cretace- ous sequence of the Sakhalin Island (see POYARKOVA 1987).

Much less exposed and more complicated tectonica1ly are Upper Cretace- ous deposits within the East Sakhalin Region, where marine, non carbonate clasties are interlayered with thick masses of acid to alca1ic vo1canogenic rocks.

The fossil occurrences, limited to marine facies, are extremely rare. Similar conditions are characteristic of the Upper Cretaceous of the ScHMIDT Pennin- sula, only a lower part of the Upper Cretaceous succession is exposed'.

WEST SAKHALIN REGION

Detailed investigations were limited to the southern part of the region, approximately to the latitude of the town Gastello, at the north-western edge of the Terpeniya Bay (see Text-fig. 2).

The Maastrichtian deposits, in spite of their remarkable thickness varia- tion,. display a twofold litho logical succession, relatively uniform allover the area, giving base to two, successive lithostratigraphic units (see Text-fig. 6).

The lower unit (bed 4 ofK.rasnoyarka Formation), corresponding to the Lower Maastrichtian, is composed of coarse- to fine-grained, brown to dark gray sandstones with tuffaceous mudstone or claystone intercalations. The unit is generally poorly fossiliferous, with macrofauna represented by single ammonite and inoceramid specimens of a bad preservation state. The upper unit (bed 5 of the K.rasnoyarka Form"tion), corresponding roughly to the Upper Maastrich- tian, is represented by mud stones, or sandy mud stones with very characteristic, oval, marly concretions. The latter are up to 50 cm in diameter and contain numerous and well preserved ammonite and inoceramid faunas.

MAASTRJCHTIAN AMMONI'n:S 281

EAST SAJC.HALIN REGION

The Upper Cretaceous deposits in the area form an extensive belt of exposures, about 250 km long in N-S direction, and up to 25 km in width (see Text-fig. 1). A very complicated tectonic structure of the East Sakhalin Region is the reason for remarkable variations in interpretations of the Cretaceous succession there. The relative position, as well as the chronostratigraphic range of the distinguished Utchirsk, Zaslonovsk, Turovsk, and Oldonsk Formations are still a matter of controversies (see e.g. SHUVAEV 1968, VERBSHAOIN & al.

1972, ROTMAN & MARKOVSKY 1992). Based on the new results of the studies in the southern part of the area, the interpretation presented by VERESHAOIN & al.

(1972) seems to be the most reliable, at least in the interval concerned, i.e.

LI.I

:z L.U

u o

:i

:z:

<C

r- a:

:c

(,,)

a::

t -

U')

<C

<C

~

<C

>- :::c

c...>

er: ~

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Fig. 3. Generallithologic and chronostratigraphic succession or the Maastrichtian stage in the East Sakhalin Region with the straligraphic ranges of selected sections; explanalions as for Text-fig. 2

282 EUlNA A. YAZlKOVA

within the Maastrichtian. Thus, within the Maastrichtian part of the succession two formations may be distinguished. The Turovsk Formation at the bottom (overlying Zaslonovsk Fonnation dated for the Campanian), and the Oldonsk Formation above. Both these two formations are regarded to be the lateral equivalents of the Krasnoyarka Formation of the West Sakbalin Region.

The whole Maastrichtian succession of the area is represented by a thick, approximately 1 km, sequence of mudstones with tuffaceous clay and sandy intercalations, and with a sparse ammonite and inoceramid fauna (see Text-fig. 3). Good biostratigraphic evidences were found only within the Oldonsk Formation where Gaudryceras hamanakense MATSUMOTO & YOSHlDA, Neogaudryceras hetonaiense MATSUMOTO, and Pachydiscus (Pachydiscus) cf.

subcompressum MATSUMOTO, as well as numerous inoceramids, e.g. Shach- maticeramus shachmati (SALNIKOVA & ZoNOVA), Sh. kusiroensis (NAGAO & MAT- SUMOTO) and Sh. shikotanensis (NAGAO & MATSUMOTO), allow to place it safely into the Maastrichtian, and the presence of Gaudryceras hamanakense MAT·

SUMOTO suggests their Late Maastrichtian age.

SHIKOTAN ISLAND

Shikotan Island, the most southerly located island of the KurH PJ- chipelago, is the only island within it with the Cretaceous deposits preserved.

The twofold Cretaceous succession is here composed (see Text-fig. 4) of

et

DOLPHIN +++ ₊₊ ++

++++

'I

CHROMOVA KRABOVAYA

lOOm

OTRADNAYA

_.-.

'-'-

Fig. 4. Uthologic and chronostragigraphic columns of selected sections in the Shi1cotan Island;

. explanations as for Text-fig. 2

MAASTRlCHTlAN AMMONITES 283

volcanogenic deposits at the bottom, consisting of basalts, tuffaceous cong- lomerates and breccias (Matakotan Formation) and of the marine mud stones with sandstone interlayers and marly concretions above (Malokurile For- mation). The ammonite and associated numerous inoceramid fauna are to be found only within the Malokurile Formation.

Two sections, one in Chromov Bay and the other in the Dolphin Bay in the western part of the Island, were studied in detail. The Malokurile Formation is represented here by 80 up to 120 m thick succession of mud stones and silts tones with sandy intercalations, and with highly fossiliferous marly concretions (see Text-fig. 4). The biostratigrapbic position of the studied successions is based primarily on the inoceramid fauna. It allows two zones to be distinguished, i.e. the Sh. sbikotanensis Zone at the bottom, and the Sh.

delphinensis Zone above. Based on the interralations of the inoceramid and ammonite schemes, known for example from the West Sakhalin successions, both inoceramid zones distinguished may be regarded as equivalents of the Lower Maastrichtian Pachydiscus japonicus Zone and the Upper Mastrichtian Pachydiscus (pacbydiscus) flexuosus - Pachydiscus (Neodesmoceras) gracilis Zone, respectively. The ammonite fauna on the Island was found only in the lower, Sh. shikotanensis Zone. The recorded forms, CalJadoceras cf. multicos- tatum MATSUMOTO, Pachydiscus (Pachydiscus) cf. subcompressus MATsuMoTo,

and Neophylloceras sp. suggest generally its Early Maastrichtian age.

AMMONITE ZONATION

The applied ammonite zonation (see Text-figs 5-6) is based on a rich collection of ammonites which were obtained during a bed-by-bed collecting in the selected sections, first of all within the West Sakhalin Region. Supplemen- tary materials came from the area of the East Sakhalin Region as weB as from the Shikotan Island.

The presented zonal scheme is based on the representatives of the ammonite superfamily Desmocerataceae. The additional scheme, based on the representatives of the superfamily Tetragonitaceae, widely used in Japan, is for the first time shown to be useful in the Sakhalin Maastrichtian as well (see Text-fig. 5) ..

Two zones, i.e. Pachydiscus (Neodesmoceras) japonicus and Pachydiscus (pachydiscus) flexuosus - Pachydiscus (Neodesmoceras) gracilis, were distin- guished within the Maastrichtian stage, based on the representatives of the superfamily Desmocerataceae (see Text-fig. 5). Both zones are distinguished within the Pachydiscus (Pachydiscus) subcompressus Superzone, regarded as a time equivalent of the whole Maastrichtian stage.

284 ELENA A. YAZlKOVA

Pacbydisc .. (Pachydiscas) subeomPftSllll Saperzoae

This zone was first distinguished within the Nayba section, by MAT- SUMOTO (1959). Some years later, its equivalent, Pachydiscus aff. gollevillensis - Pachydiscus subcompressus Zone was applied by VERBSHAGlN (1963) where- as the Pachydiscus subcompressus Zone, as the uppermost Cretaceous am- monite zone on the Sakhalin was formally accepted by the All-Russian stratigraphic Union in 1974. The lower boundary of the Zone, i.e. the appearance level of the index taxon, Pachydiscus (P.) subcompressus MAT- SUMOTO, is regarded as nearly corresponding to the lower boundary of the Maastrichtian stage. The upper boundary coincides with the final extinction of the ammonite fauna, approximating thus the K{f boundary.

Padiydilcus (padlydiscus) japoaicas Zone: Interval Range Zone

The lower boundary of the zone marks the appearance level of the index taxon. The upper boundary delimits the first occurrence of the representatives of the species P. (P.) jlexuosus MATSUMOTO, or P. (N.) gracilis MATSUMOTO.

rI.I

I

~ AMMONITE

...

~ -§

ZONATION

I>esnlocerataceae Tetragonitaceae

rI.I rI.I

:-

=-

Pachydiscus (p.) ^m Zelandites

~ ~

a

_-

I

S;

~

GaudlYccras

U ^{gracilis .J:J gracilis} bamanakense

;

E

~ Pachydiscus (p.) ~

:a

~ ^~

B

_~ ^fa

S

I

indra

Japomcus

i

i

awaJlcDlIlII Canadoceras

multicostatum

~ Patagiosites Tetragonites

~

Pachydiscus (p.)

~

fasciCDstatus

Fig.

s.

MAASTlUCtn'lAN AMMONITES

Ammonite

zonation Ammoniterangcs

285

Fig. 6. Stratigraphlc distribution of the ammonite species in the Campanian and Maastrichtian deposits of the SakhaJin Island and the Shikotan Island .

This zone corresponds to the Zone P. japonicus - D. hetonaiense of MATSUMOTO (1959), recognized by this author on the Hokkaido Island (see also MATSUMOTO & TAKAYANAGI 1982). In the inoceramid scheme it approximates the range of the Shahmaticeramus shikotanensis Zone of ZoNOVA (1992).

Besides P. (N.) japonicus MATSUMOTO, the characteristic ammonite species occurring within the Zone are P. (P.) subcompressus MATSUMOTO and Neophyl- loceras ramosum (MEEK). Moreover, the frequently occurring are the inoceramid species Shahmaticeramus shikotanensis (NAGAO & MATSUMOTO) and lnoceramus pectiniformis ZoNOVA.

The species P. (N.) japonicus MATSUMOTO is known also from the north-eastem Russia (see DUNDO 1971) where it co-occurs with Pachydiscus kamishakensis JONES. The latter species, as well as Pachydiscus alaskensis JONES,

found there, are the typical forms of the lower Maastrichtian strata of southern Alaska (JONES 1963).

286 ^{BLENA A.} YAZIKOVA

PadlydISCIB (PadaydiscIII) DexaO!IIS - ~ (Neodesmoceras) gracllIs Zone: Interval Range Zone This zone was recognized for the first time by MATSUMOTO & TAKAYANAGI (1982) on the Hokkaido Island, and recently recognized by the Author in the Sakhalin Maastrichtian. Presumably, it corresponds to the P. neubergicus - P. gollevillensis Zone, distinguished in Kamchatka. It is suggested by the ammonite species: P. (P.) flexuosus MATSUMOTO, N. ramosum (MEEK), and N. hetonaiense MATSUMOTO, common to both regions.

The lower boundary of the zone marks the first occurrence of any of the index taxon. The upper boundary is placed at the final extinction level of the ammonite fauna marking the end of the Cretaceous.

The ammonite fauna recorded within the Zone is variable though the particular forms are rather rare in the analyzed sections. Among the most characteristic are the following: P. (P.) flexuosus MATSUMOTO, P. (N.) gracilis MATSUMOTO, P. (P.) gollerJillensis (O'ORBIGNY), P. (P.) neubergicus (HAVER), P. (P.) subcompressus MATSUMOTO, Zelandites japonicus MATSUMOTO, Z. varuna (FORBES), Neophylloceras hetonaianense MATSUMOTO, and N. ramosum (MEEK).

Of the common non-ammonite fauna first of all are the inoceramids, represen- ted by Shahmaticeramus shahmati (SALNIKOVA & ZONOVA), Sh. kUfiiroensis (NAGAO & MATSUMOTO), Sh .. ruhkusiroensifi ZoNOVA, Sh. pilovensis (SOKOLOV), and Sh. delfinensis (SALNIKOVA & ZoNOVA).

The supplementary zonal scheme based on the representatives of the superfamily Tetragonitaceae comprises one Superzone, Zelandites varuna, divisible into three zones. From the top downward these are as follows (see Text-fig. 5): the Pseudophyllites indra Zone, the Gaudryceras hamanakense Zone, and the Zelandites japonicus Zone.

Zelaadites vanma superzoae

This superzone comprises the interval from the first occurrence of the index taxon to the final disappearance of the ammonite fauna. In the chronostratigraphic scheme it approximates the whole Maastrichtian stage.

The zone was firstly distinguished by MATSUMOTO (1959) within the Cretaceous of the Sakhalin and Hokkaido Islands.

Pseudophyllites

mdr.

The interval from the first occurrence of the index species to the appearance level of the species Gaudryceras hamanakense MATSUMOTO & YOSHIDA. This zone was firstly distinguished in Nayba section, southern Sakhalin by MATSUMOTO (1959), who later recognized its applicability in the Japanese Cretaceous. Besides the index taxon, the species Neophylloceras ramosum (MEEK) and Gaudryceras denmanense WHITEAVES, are the most characteristic elements within the Zone.

MAASTRICH'I1AN AMMONl1U 287 Gaudryc:eras ... nakense Zoae: Interval Range Zone

The lower boundary is placed at the appearance level of the index taxon and the upper boundary at the entrance level of the index taxon of the succeeding Zone, the Zelandites japonicus (see Text-fig. 5). The Zone was originally distinguished by MATsuMoTo (in: MATsuMoTO & TAKAYANAGI 1982) in Japan. It is easily recognizable in the Cretaceous of the West and East Sakhalin.

Zelaadites japonlcus Zoae: Taxon Range Zone

The Zone is proposed here for the first time. AB the stratotypic section the Krasnoyarka succession (see Text-fig. 2) is here suggested. The Zone is well developed in the Cretaceous of the West Sakhalin Mountains. The index species Zelandites japonicus MATSUMOTO is known also from the Upper Cretaceous of Japan (MATSUMOTO 1938).

SYSTEMATIC ACCOUNT

Seventeen species respresenting seven genera are described. The sys- tematics is applied after MIKHAILOVA (in: BOOOSLAVSKAYA & al. 1990). All specimens are stored at the Geologic Museum of the All-Russian Geological Institute, St.-Peterburg.

The following dimensions are measured: D - diameter; Wb - Whorl breadth; Wh - Whorl height; U - umbilicus; all dimensions are given in millimeters.

Class Cepbalopoda CUVIER, 1797 Subclass Ammonoidea ZrrrEL, 1884

Order PhyUoceratida

1950 Suborder Pbylloceratina

1950 Superfamily PhyDoceratacae

Family PbyUoceratidae ZiTTEL, 1884

Genus Neophylloceras SHIMIZU in: SHIMIZU & OBATA, 1934

TYPE SPECIES: Ammonites (Scapltltes?) ramosus MI!EK, 1858, from the Maastrichtian of the Vancouver Island, Canada.

Neophyllocera.fI ramosum (MEEK, 1858) (PI. 1, Figs 9-10)

1876. PhJlll_lII'l_ (MIIIC); F.B. MUIt, p. 371, PI. 5, Fi .. I.

1942. N.",lrytloura.r _ (Maut); T. MAmlMlJl"O, p. 674. Text-f . . 1-2.

1952. NupltyUoc.u _ (M1IIJt); J.L. UIII .. , p. 59, PI. I, Fip 4-5.

288 BLENA A. YAZlKOVA 1958. PltyllDCHtU IVIIfJIMIIIfI (MBII1<); F.M. ANDIIUON, p. 181, PI. 58, Fig. 4.

19~. NHpllyl"-rtu_ (M"K);T. MAT8IlMI'II"(~ p. I, PI. I, Pi .. I; PI. 2, Fil. 2; PI. 8, Fis.1.

1963. Neopltyl/tJt:.u".".,..."" (MBII1<); D.L.

J,_

1970. NtJOphy/Jo«ral_ CM"",,); R.A. HBNDBUON, p. 5, TClIt-fJ .. 2a; PI. I, Fi .. 3.

HOLOTYP£: The &peeimcn or MI!I!I< (18511, p. 45) from the Maastric:htian of the VaneouVlll' Island, Canada.

MATERIAL: Seven specimens.

West SakhllliD: Specimen No. 118/12769 from Kram."ma 1ICCIIi0D IUId IfJIlCimcaI NUl 417/10693 aod 21/12632 from Mllkaro'Y8 1Cdi08, P. (P.) IIIbc:omprcnul Suporzmc.

Shikotan lIIaad: Specimenl No. 4/12757 and 29/12632 from Dolpllin ..wOD, P. (p.) IUbllDmp ... SupcnDllc.

Kamdlatta: Spac:imcal NOI 144/12769 aod 18/12632, from Nildckuyul Scdi08, P. ncub ... aicu. - P. aoDCYillenoil Zo8C.

DIMENSIONS:

Specimen D Wb Wh

-

144/12769 70 12 32 5 46 ^]7 2.6 7

118/]2769 27 3 17

-

-

18/12632 107 32 52 8 49 45 1.6 4

DBSCRIYfION: Markedly involute, moderately compressed laterally, discoid in shape.

Ventral side narrowly rounded. Whorl section oval, high. Umbilicus narrow, deep. Umbilical wall steep, Oat with umbilical shoulder rounded_ Ornament consisting of lirst and second order ribs.

First order ribs arise at the umbilical shoulder, branching approximately one third of the whorl height into 4 to 5 secondary ribs. Slightly Oexuosus on lateral sides pass onto ventral side with some ribS bifurcating. On ventral side the ribs slightly curve foreward.

DISCUSSION: Prom very similar species Neophyllocero., subramo.fum SPATH, the MEEK's species differs in possessing convex bullae at the umbilical shoulder and in much more pronounced ribs at the fmal growth stage.

OCCURRENCE: The species is known from the Campanian - Lower Maastrichtian of the

Vancouver'Island, from the Turonian through Campanian of California, Upper Maastrichtian of southern Alaska, and the Campanian - Maastrichtian of Japan and Kamchatka. In the studied area it occurs in the Turonian through Maastrichtian of the Sakhalin Island and in the Upper Maastrichtian of the Shikotan Island.

Neophy/loceras hetonaiense MATSUMOTO, 1942

(Pt. 1, Figs 5-7)

1942. Nt1OPltyl"-rtu Iwlonllit!lU1I MA11IUMUto; T. MAlSuNaro, p. 67S, TClIt-fJli la3, b3.

1963. Neophyl"-rtu 1w11Jlll:M1U1I MAlSUIIIOI"o; D.L. J ... p. 23, PI. 6, Fip 9-10.

1990. NHPhyllo«nu Iwl000alertift! MAlSUNIJI"o; EA ZoN..,..A, PI. D, Fig. 6; PI. E, Fig. 8.

1991. NHphyllo«nu Iwl000aIt!rtN MAmlNMo; EA. YAZIItOYA, p. 71, PI. 2, VIB. I.

1992. NHPllylktt:mu IwIMan. MA11IUNoro; B.A. Y AZOCIJYA, p. 194, PI. 110. Fill 3-5.

LECTOTYPB: The specimen illustrated by SPAn! (1953, PI. 5, Fig. I) from the Upper Mulilrichtian of the Hctonw area, Hokkaido Island, Japao.

MATERIAL: Five specimens.

Bail Sakbalin: Spec:imml NOI 132/12769, 16112621, 154/12632, 24/12632 and 178/12632 from Ncrpidl)"8 lCClion. O.

bamaallk_ Zone.

MAASTRlCHTIAN AMMONITES 289

DIMENSIONS:

Specimen D Wb Wh U fWh/D(% Wb/D(°1. Wh/Wb U/o(%)

132p2769 32 6 10 2 31 19 1.7 6

24 12632 34 8 17 3 SO 21 2.1 8

17a/I2632 29 S

- -

^-

154/12632 39 8 16 4 41 21 2.0 9

DESCRIPTION: Involute, discoidal in shape with slightly COllvex lateral sides. Ventral side narrowly rounded. Whorl section oval. Umbilicus narrow to very narrow. Umbilical wall flat with rounded umbilical shoulder. Ornament consists of primary and secondary ribs. At early stages weD deveJoped umbilical tubercles. Rib clusters well seen almost on the whole lateral sides of the whorls;

they consist of primary ribs, but the one third of the whorl height the secondary ribs appear.

Flexuously shaped ribs are more and more pronounced with the growing diameter.

DISCUSSION: The more pronounced involutness, narrower umbilicus and much more convex lateral sides well distinguish this species from the very close species Neophylloceros ramosum (MEEK).

OCCURRENCE: The species is recorded from the Maastrichtian of Japan, New Zealand, Chile, and India. It is known from the Upper Maastrichtian of southern Alaska, California, and Vancouver Island, Canada, Kamchatka, as well as from the Crimea in Europe. In the studied area it was found in the Maastrichtian of the Sakhalin Island.

Order Lytoceratida

1889 Suborder Lytoceratina

1889 Superfamily Tetragonitacae

1900

Family Gaudryc:eratidae SPATH, 1927 Genus Zelandites MARSHALL, 1926

TYPE SPECIES: Zelandites kaJporoell8is MARSHAu. (1926, p. 147, PI. 19, Fig. 9; PI. 31, Figs 1-2) from the Campanian of New Zealand.

Zelandites varuna ^(FORBES, 1846) (PI. 1, Fig. 8)

1846. A.mnumIIa 1IIJ1I/IIIJ; E. FIIUIIII, p. 107, PI. 8, Fii-S . .

HOurrYPS: Tha specimaJ i11ustn1cd by F _ (1846. p. 107, PI. 8, Fia. 5) Crom the MUWidiIiaD ~ IOUlhcm 1Ddia.

MATERIAL: Two specimens (Nos 100/12769 and 181/12769) from West Sakhalin (Pugachcvka section), O. hamanakense Zone.

DIMENSIONS:

Specimen D Wb Wh U Wh/D(% IWb/D(% WhfWb UfD(%)

181/12769 14 4 3 2 30 21 1.3 17

24/12632 42 17 11 IS 40 28 I.S 35

290 BLBNA A. YAZlKOVA

DESCRIPTION: Semiinvolute, slightly convex laterally. Ventral side narrowly rounded.

Whorl section ellipsoidal in shape much higher than wide. Umbilicus relatively wide, shallow with steep umbilical wall and with rounded umbilical shoulder.

DISCUSSION: From Z. iIIf/olJU (JIMBO) the species may be distinguished by its ]ower grade of involutness, more compressed lateral sides and wider umbilicus. Moreover, Z. IKII'Una (FORBIlS) possesses relatively well expressed ornament while JIMBO'S species is almost smooth.

OCCURRENCE: Maastrichtian of India. Japan, Sakhalin, Chile, and Seymour Island. In the studied area known from the SakhBlin Island.

Zeiandite.'l japonicus MATSUMOTO, 1938 (PI. 1, Figs 14 and PI. 2, Figs 1-18)

1938. ZdlllfllII. CIlIUM (1' . . _ ) var.~ T. MATIUWI'O, p. 140, TCII1.-I".,. I; PI. 14, ... ,.. ~7.

1976. Z«1ftIJI .. ~ MATSI.MCII"o; V.S. ~ p. 7 ... PI. 90, ... 1-5.

I!IIII. ZMIIIIIDt .. ...,.. (F->; T. MA ... nro, p. 18", PI. SI, Fig. .. . 1991. Z«IIIIIIitttIjqt1tflew MATalNoro; I!.A.. YAZIKOYA, P. 11.1'1. 2, ... 2-

HOI.OTYPB: The lIpCI:imea ilUIInlad by MAT ... ".., (1938, P. 140; PI. I", Fi .. 7) (rvm !he Muatricbliu oftbc Nayballl!dioa, _tbc:m SatbaIiD.

MATERIAL: Fourty four specimens.

Wool Sakbalia: Spocimm No. 101/12769 rrom Pupdu..talCClioa; spociaJ:la. NOI 3/12913, 4/12913. 6/12913 tbro ... 11/12913, 85/12769, 86/12769,103/12769tbrouih 119/12769.99/12769. 12 .. /I2769tbro ... 131/12769.148/1276Otbrouah 151/12769, 153/12769,106&/12769, UId 13l1li/12769 fmm 511111Y. lCCIion, z.japonicu. Zona.

ICamdlltka: Spcc:ima No. 2/12913, P. Deubcl'Jicu.-P. aoi1cWlCll1i1 Zone.

DIMENSIONS:

Specimen D Wb Wh U ~JD(% WbfD(% WhfWb U/D(%)

86/127611 3D 13 7 5 43 23 J.9 17

103/12769 47 19 9 8 41 19 1.2 17

104/12769 29 11 !I

..

105/12769 25 10

•

106/12769 30 8 6 5 26 20 1.3 16

IffT/12169 24 10 !I 3 40 38 1.1 25

108/12769 21 9 6 4 33 28 1.1 19

110/12169 25 I 8 5 36 32 I.I 28

111/12169 20 9 1

..

113/12769 32 11 8

..

1211/12169 21 8 6

..

121/12769 24 9 1 3 38 29 1.3 25

122112769 11 6 5 3 35 30 1.1 11

124/12769 45 16 9 5 36 20 1.8 11

125/12769 45 11 12 5 31 27 1.4 11

127,12169 30 10 7

..

141/12169 23 8 7

..

151'12760 31 12 ^!J 5 39 29 1.3 16

153/12760 39 13 9 5 33 23 1.4 13

REMARKS: The surface is almost smooth, only some elements appear on the most adult parts of the whorl. The species Z. varuna (FORBES) is much less involute, less convex and possesses easily detactable ornament.

MAASTRlCH11AN AMMONITES 291

OCCURRENCE: Maastrichtian of Japan and Kamchatka. In the studied area Umited to the Upper Maastrichtian, Z. japonicus Zone, of the Sakhalin Is1and.

Genus Gaudryceras GROSSOUVRE, 1894

1YPB SPBCIBS: Ammonites mitis HAtmR (Sft! BOUU! & al. 1906) from the Campanian of Germany.

Gaudryceras denmanense WHITEAVES, 1901 (PI. 6, Fig. 1 and PI. 8, Fig. 2)

1901. L y t _ (GaIIdt,_) "--Mw, l.P. WII/TM-. p. 31.

1952. Gtllldrycmu dmmtlMIIM WIIlRAva; J.L. U_a, p. 60, PI. <t, Fig. I.

1971. GtIIIdry_ " - - _ WnrrIIAva; O.P. Dul<DO, PI. I, Fi&, 2.

1992. ~_ ... _ WIIITBAva; BA Y.umwA, p. 195, PI. 3, Fit. 3.

LECl'OTYPB: The ~ reported by WHInAVU (1901, p. 32) from the Campuiu ~ British Columbia, noiJIalltated by U _ (1952, PI. 4, A .. I).

MATBRIAL: Three specimens.

Welt s.thaIin: ~. Nu. 27/121132 aDd 123/12769, Matarova sectioa, P. (P.) tIIIIxlompreaus Supcrzooe.

Ea. Sathalin: Spa:imen No. 111/12769, NerpidIya D1iDII, P. (P.) IUbaompn:uas Silpenonc.

DIMBNSIONS:

Specimen D Wb Wh U Wh/D(%) WbfD(% WhfWb

1

'l3A1

8812769 124 44 40 SO 35 32 1.1

U/D(%) 40 40

DESCRImON: Medium size for the genus, semiinvolute, with invoJulness approximately SO%. Lateral sides convex, ventral side rounded. In early stages the whorl section almost circular, slightly wider than high. Then, the height becomes gradually greater than width and the whorl section becomes oval. Umbilicus wide, with low, rounded umbilical waJ1 and rounded umbilical shoulder.

Juveniles possess very weak ornament consisting of numerous, faint pr.imary and secondary ribs. The latter arise at the umbilical shoulder and disappear in the middJe of the JaUeral side, or

they arise in the mid-height of the whorl passing onto the ventral side. Both primary and secondary ribs curve foreward on the ventral side. On the 3th to 6th whorls rare constrictions.

Adults possess wide, weakJy convex, evenly distributed primary ribs, and rare but well deveJoped secondaries that appear in the mid-height of the lateral side and pass onto the ventral side.

RBMARKS: The presence of the more COD vex ribs and constrictions associated with swells and their Jower number per whor1 distinguishes this species from GaudryC4!rtlS rJenustum MAT-

SUMMO.

OCCURRBNCE: Maastrichtian of Canada, Japan and Campanian of California. In the studied area found in the Maastrichtian of the SakhaJin Island.

292 BLENA A. VAZIKOVA

Gaudryceras hamanakense MATSUMOTO & YOSHIDA, 1979 (PI. 3, Figs 2-3; PI. 4, Figs 1-3; PI. 6, Figs 2-3)

1960. GflIIIiryemI.r afT. /cayri (FlUES); s. V<BIUDA, p. 2, Toxt.rlll. 2.

1979. GawJrycmJ8 honuuto/c_; T. MAnuNurn a: s. YOIllIIDA, p. 68, PI. 10, Figs 1.5; PI. 11, Fias 1·2.

1990. GllllllrYCtlrtl8lu1mtmalc_ MAlIIulftrrn a: YOIIIIIDA; EA. ZaNOWA, p. 33, PI. I, Fig. I.

1991. GawlryCtlrtl8lu1mtmalct!ll# MAnulftYrn a: VOIIIIIDA; M. VAZm.WA, P. 68, PI. I, Fil!. I.

1992. GllllllryCtlrtl8lu1m1lllllhrw! MAnUNtYro& YIlIIIIIDA; M. YAZlIWYA, PI. llD, Fip 1·2; PI. 111, Fipl.2.

HOLOTVPB: Thc sp.:amcn illuslratcxl by MATllJNOfn a: VOIInDA (1979, PI. ID, Figs 1·3), from the Upper Maa,trichlian of the Hokkrrido IsIaod, Japan.

MATERIAL: Twenty three specimens Crom West Sakhalin.

MKarovaICOtioU: Spccim .... NDlI/I2621 through 7/12621,10/12621.22/12632,23/12632,25/12632. 26/12632,12/12913 tblough 14/121113, and 424/10693; O. blllWlKealc ZoDe.

Kr8IDoy1lrlo:alll>Ctiou: Speamcn No. 133/12769. O. hamaoalttllllC Zone.

Pllpdllnb lCdiou: sp.amCflI NOM 79/12769, 146/12769, 102/12769, amlI14/12769; 0, hamlllllllttllMC Zouc.

Niluy lCdiou: Specimen No. 8/12621, O. hllJDauakeose Zoue..

DIMENSIONS:

Specimen D Wb Wh U Wh/D(%) ~b/D(%) Wh/Wb

26/12623 50 13 13 25 26 36 0.7

25/12623 95 24 24 45 2S 43 1.0

146/12769 70 23 28 34 33 40 0.7

137/12769 86 26 23 3S 30 28 1.2

79/12769 77 24 22 ³⁴ 30 29 1.1

114/12769 66 19 . 21 26 29 30 0.9

133/12769 44 12 18 20 27 40 0.6

U/D(%) SO 43 49 41 44 42 47

DESCRIPTION: Medium size Cor the genus, evolute passing to almost semiinvolute in adu1ts, moderateJy inflated. Vent raj side uniformly rounded. Early whorls wider than high, becoming gradually higher than wide in adults. Umbilicus wide, shallow, with rounded umbilicaJ shoulder. Ornament consisting of Caint, flexuous, numerous ribs, arising at the umbilical shoulder passing onto ventral side With slightly curving at the mid-flank. On the outer flank and ventral side tiny secondaries occur. Adult whorls bear rare, 3-4 per whorl and up to 5 on the last whorl, constrictions. Ribs become thicker on the last whorl.

REMARKS: From Gaudryceras tknma1Umse WHITEAVIlS, the species differs in having more numerous primary and secondary ribs, greater number oC constrictions and less thick and high ribs on the last whorl.

OCCURRENCE: Upper Maaslrichtian, G. hamanaltense Zone, of Japan. In the same stratigrap- hic position known Crom the Sakhalin Island.

Gaudrycera.v venusturn MATSUMOTO, 1984 (PI. 5, Fig. 2; PI. 14; PI. 15, Fig. 2)

1984. GaudryCt!rt18 1If!1I1Utum; T. MAnIJlolOfI~ p. S; PI. 3, FiBI 1·2.

HOLOTYPE: 'The specimen i11ll1llrated by MAl'SllNOI"o (1984, PI. 3, Figs 1·2) from the Upper Maastrichliau of the Killsu IIland.

JBpau.

MAASl'lUCHTlAN AMMONITES

MATERIAL: Three specimeos from West Sakhalin.

PupdlcW:a 1Cdion: Spccimeal NOI 134/12769 and 75/12769, O. hamanatcnsc Zone.

Matuova 1Cdion: SpcciDICII No. 136/12769. O. bamllllllkcnsc ZoIlC.

DIMENSIONS:

Specimen D Wb Wh U Wh/D(%

75/1'1:169 130 45 40 40 35

134/12769 160 70 50 47 44

136/12769 130 SS 40 4S 42

293

Wb/D(% Wh/Wb U/D(%)

31 1.7 31

31 lA 23

31 1.4 35

DBSCRImON: Large size for the genus, semievolute, weakly inDated. Ventral side oval, rounded. Last whorl quickly increasing in size toward aperture. Whorl section oval, higher than wide. Umbilicus varies between wide to moderately wide with low umbilical wall. Ornament composed of evenly spaced primary and secondary, Oexuously shaped ribs. Primaries arise at the umbilical shoulder, and the secondaries at the mid Dank; both curve slightly foreward. At the juvenile the secondary ribs appear every two primaries, and then, toward the adu1t, every three.

Finally they are unevenly distributed. Moreover, there occur rare (usually 4 ribs per whorl and on the last whorl up to 6) thick, inDated ribs, with even interib interval, branching into two at the ventral side.

REMARKS: From G. Iw_kense MATSUMOTO this species difTers in a lower number of ribs, the presence of thick, inflated ribs on the surface of the last whorl, and the pattern of appearance of the secondary ribs at the juveniles.

OCCURRENCE: Upper Maastrichtian, G. hamanakense Zone, of Japan. Known from the same zone from the Suhalin Island.

Family Tetragonitidae HYATT, 1900 Genus Tetragonites KOSSMAT, 1895

TYPE SPECIES: Ammonites timolMQ11U8 PrCTET, 1847 from the Upper A1bian of France.

OCCURRENCE: A1bian through Campanian of the Pacific Region and A1bian - Q:nomaniao of the Medditerranean.

Tetragonites popetensis Y ARE, 1903 (PI. 3, Fig. 1)

1903. T~frlgolfi'e6,.rt-u; H. YAIID, p. 48, PI. 7. F'IP~. 6.

1 984. T~frIIlOIIi't!S popetellllB YAlE; T. MATsUMaro, p. S2, PI. 23, Fi .. 3.

HOLOTYPE: TIle spcQmm illusUalod by Y Ma (J 903. PI. 7, Fi .. 4) rrom the Upper Ounpenian m the Hotltaido 111al1d. Japan.

MATERIAL: Two specimens from West Sakhalin.

Nayba lGdioo: SpccirDm No. 76/127698, T. pOpc\ClIsil ZolIc.

Kura 1OCIi0ll: Spccimoll No. 15/12913, T. popotcnlil Zone.

294 ELBNA A. YA7.DC.OVA DIMENSIONS:

DESCRIPTION: Semiinvolute. moderately compressed. Ventral side triangular, rounded.

Whorl section pentagonal, rounded, higher than wide; Umbilicus shallow, with moderately wide, vertical umbilical wall and rounded shoulder. Whorl surface almost smooth bearing only growth lines. In adults appear evenly distributed distinct, deep constrictions, which arise at the umbilical shoulder and curve markedly foreward on the flanks.

REMARKS: This species differs from the close TelrQgoniles superslUS VAN HOFPEIIT in much wider umbilicus, in being more compressed, the pentagonal shape of the whorl cross section and the occurrence of constrictions.

OCCURRENCE: Known from the Santonian-Campanian of California and Campanian of Patagonia. In the studied area T. popetensis YABE was recorded from the Upper Campanian, T.

popetensis Zone, of SakhaIin.

Tetragonites epigonus KOSSMAT. 1895 (pi. 5, Fig. 1)

1895. Lytoc6tU (TetrqOlllta) "Pirolllll; F. KOIIIMAT. p. 135, PI. 17, filii 4-5. 10.

1977. T~t7a8tMlta d. w-K~T; WJ. KIooa;oy.t: H.C. KuNaaa, p. 165, TelI1.r ... 9.

LECTOTYPE: The IIpCCimI:II iUlllltatod by K .... AT (1895, PI. 17, Fil-4) from the Campani811 of lodia, by IUhaoquCllt designation of KilNMlDv .t: KuNIJIIIl (1977).

MATERIAL: Three specimens from the West SakhaJin.

Na)iIa sedion: Spccimca No. 98/12769, T. popcb:ollil Zone.

Krasnoylltka lCCIion: Spcc:imolll NDI 77/12769 aDd 78/12769, T. popclenllilZone.

DIMENSIONS:

DESCRIPTION: Semiinvolute, inflated, with widely rounded ventral side. Whorl section subquadrate, rounded. Umbilicus moderately narrow, shallow with vertical umbilical wall. Whorl surface smooth with only growth lines and rare constrictions, being curved on the ventral side backward, and with fleXllous shape on the flanks.

RBMAR K.S: From T. popelensis Y ABH this species differs in more narrow umbilicus, greater inflation, different whorl section and another characteristics of the constrictions.

OCCURRENCE: Known from the Turonian through Santonian of southern India. Antarctida, Angola, Madagascar, South Africa, southern France, and Canada. In the studied area reported from the Campanian strata of the Sakhalin Island.

MMSTRlCHTlAN AMMONlmS

Order Ammonitida

1884

Suborder Perisphinctina

1983 Superfamily Desmocerataceae

1895

Family Pachydiicidae SPATH, 1922 Genus Canadoceras SPATH, 1922

295

TYPE SPBClES: Ammonites newherryannus MEIlIt, 1876, from the Campanian of Brilish Colum- bia, Canada.

OCCURRBNcB: Known from the Santonian throu,fl Campanian of Madagascar, Japan, Canada, California and Brazil. In the studied area found In the Santonian - Lower Maastrichtian of the Sakhalin Island and from the Lower Maastrichtian of the Shikotan Island.

Canadoceras multicostatum MATSUMOTO, 1954 (PI. 11, Fig. 1 and PI. 12, Fig. 2)

1954. ~ru IfIfIItlt»lttlhllrl; T. MAmNlII'O, p. 304, Tcott-r ... 28; PI. 34, Fip 1·2.

1984. C._DUra IftIIItictJlttatum MATSuwaro; T. MATS .... oro, Part I: p. 19, PI. 3, Pip 1·3; Part D: p. 47; PI. 18, Fill I -2; PI. 20, Fi .. 2.

1987. CattatIDurtU "",ui_,-MATSUYoro; Z,N. PtwAUOYA, p. 142, PI. 28, Pi" 3.

HOUlTYPE: The..,.,an:..a illullrded by M"TSllMOfO (1954, Tw-r ... 28 I11III PI. 34, Pil. I) rrom Ibe Upper Campomian 0( the Sakbalia bWId.

MATBRIAL: Six specimens, rrom the West Sakhalin.

KrallloyarU lCdioa: Specimco. Nos 18/12913 and 418/10693, C. mulliaw'lnm Zoae.

Mak8l'OY. 1IlIlIJoa: No. 115/12769, C. multicoltalam ZDne.

DIMENSIONS:

DESCRIPTION: Large size for the genus, moderately compressed. Ventral side widely rounded. Whorl section oval, higher than wide. Umbilicus relatively narrow, deep, with moderately steep umbilical wall and rounded umbilical shoulder. Ornament at the juvenile consists of thin.

inflated ribs, arising just above the wribilical shoulder. Approximately at the mid-flank the secondary ribs arise. Both, primary and secondary ribs pass onto the ventral side where they curve stightly foreward. The similar shape possess the rare (usually 4 per wborl) constrictions. At adults tJie ribs become thicker and the constrictions become deeper.

REMARKS: The species CtJlllldoceras kOSS1nati MATS1.IMaTO possesses more inflated form, much larger umbilicus, more distinct ornament, and another characteristics of constrictions.

OCCURRENCE: Upper Campanian of Japan. In the studied area known from the Campanian and lowermost Maastrichtian of the Sakhalin Island.

296 ELBNA A. YAZlKOVA

Genus Patagiosites ^SPAlH, 1953

TYPE SPECIES: Ammonites J?Illagiosus San.cma, 1867, from the Campanian of Germany.

OCCURRENCE: Known from the Campanian through Maastrichtian of the north-weatern Europe, Patagonia. California. Alaska, and from the Lower Maastrichtian of the Kamchatka.

Patagiosites a/askew JoNES, 1963 . (PI. 9, Fig. 2 and PI. 20, Fig. 3)

1!l63. I'lIIiIPiI/Iu fIIIItIrftrir, J _ P. 45. TeK1.r ... 24-25; PIa 31-40, PI. 41. Fip 1.3,7.9.

HOLOTYPB: 1"bD IfIIIICimm illustrated by J .... (1!l63. PI, 411-41. Pip 1,7) from th" Lower MustridJtillll or lOuihlnl AJastL

MATERIAL: One specimen (No. 143/12769) from Penzhina Section, Kamchatka; P. kamishaken- sis Zone.

DIMENSIONS:

DESCRIPTION: Semiinvolute, with involuteness about 70%, compressed. ventral side narrowly rounded. Whorl section triangular, oval. Umbilicus moderately wide, shaDow, with moderate1y steep umbilical wall and rounded shoulder. Ornament, at the juveniles consists offaint, evenly spaced nos, growth linea and constrictions. One deep cons1riction oa:ur every three ribs.

Growth linea distributed in interrib intervals as well as between ribs and constrictions. Adults possess more markedly developed, deeper constrictions, and singular, unevenly distributed ribs and growth linea inbetweel1. All ornament elements are Oex.uously shaped, and curve foreward on the ventral side.

REMARKS: Prom close form Pataglosilu compreS8US (MATSUMOfO) the species dilTers in triangularly rounded whorl section, shallower umbilicua, leas steeper umbilical waD, and less pronounced ornament at the middle stage of growth. Moreover, at the IaUer stage the number of ribs is distinctly lower. .

OCCURRENCE: Lower Maastricbtian, P. kamishakensis Zone, of southem Alaska and Kam- chatka. Not reported formerly from the studied area.

Genus Pachydiseus ZI1TEL, 1884

TYPE SPECIES: Ammonites neubergicus HAUElI., 1858, by subsequent designation ofGRossol.MlB (1894) from the Maastricb.tiaD of southern Europe.

Subgenus Pachydiscus ^ZITTEL, 1884

Pachydiscus (Pachydiscus) neubergicus (HAuER, 1858) (PI. 13, Fig. 1)

18,.. ~'a ~ HA .... P. 12, PL 2, rqsl-3; PI. 3. rIP 1·2-

1194. I'tdydllt:tu"...",/I:Ji$ (HA\lIIIl); A. Oil...,.",.., p. 207; PI. 27. FiJI. 3; PI. 30. FiJI. 4; PI. 38. FiJI. 3.

I !lOll. PtdydlMlu MIIiJ",./I:Ji$ (HA\lIIIl); J. NowAK. p. 769. PI. I, FiJI. 6.